30 or 40? How to know which numbers are the best “Engine oil” for you?

The viscosity of the engine oil, or according to the SAE standard, is the level of oil thickness. If the engine oil is too thick, it can’t circulate well enough to lubricate the engine. But if the engine is too fluid, it can’t protect the engine parts well either. You need to choose the right engine oil number to extend its life and allow our beloved car to perform to its full potential.

From the usages:

• Heavy usage, e.g. regularly carrying heavy objects, driving on mountain roads, on steep terrain, etc. will cause the engine to wear more than usual. You should use a high-viscosity grade such as 5W-40.
• General usages, e.g. a car that is normally used and drives a short distance. Driving in the city You should choose a low-viscosity number, e.g. engine oil with the number 5W-30.

From the mileages: 

• Cars with a mileage of less than 150,000 km should use engine oil with the number 5W-30, as the use of a higher viscosity number can be another cause of engine sluggishness. consumes fuel as it cannot circulate as well as it should.
• Cars with a mileage of more than 150,000 km should use engine oil with the number 5W-40, as the engine begins to wear out. There is a gap between the parts of the engine. Engine oil with a high viscosity number can fill the gaps well.

It’s important to consider both points. For example, your car is an all-purpose vehicle, but it’s an old car with more than 150,000 km on the clock. You should choose engine oil with the number 5W-40. In other cases, e.g. if it’s a vehicle for freight transportation, even if it has run less than 150,000 km, you should choose 5W-40 to match the engine’s performance.